Pitot pump with slotted inlet passages in rotor case

ABSTRACT

A pitot pump, i.e., a centrifugal pump, comprising a rotary casing, means for delivering a fluid to be pumped to a pumping chamber in the rotary casing, and a discharge duct coaxial with the rotary casing. The pitot tube is disposed in and extends radially of the rotary casing and is provided adjacent its outer end with an inlet facing in a direction opposite to the direction of rotation of the rotary casing, whereby the inlet receives fluid from adjacent the periphery of the rotary casing with a ram effect. The rotary casing is provided with open slots, generally radial, for conveying the fluid to be pumped from the central portion of the pumping chamber to the periphery thereof.

Mar., 5, 1974 United States Patent Erickson et al.

Primary Examiner-Carlton R. Croyle [541 PITOT PUMP WllTH SLOTTED INLETPASSAGES IN ROTR CASE Assistant ExaminerLouis J.. Casaregola Harris,Kern, Wallen &

Attorney, Agent, or Firm- Tinsley [75] Inventors: John W. Erickson,Huntington ABSTRACT Beach; Carter P. Williams, La Crescenta; Ralph F.McArthur, Huntington Park, all of Calif.

4 Claims, 2 Drawi Figlia-es PATENTEUHAR 5974 SHEET 1 0F 2 PITOT PUMPWITH SLOTTED INLET PASSAGES IN ROTOR CASE BACKGROUND OF INVENTION Thepresent invention relates in general to centrifugal pumps and, moreparticularly', to a centrifugal pump of the pitot type, such a pumpcomprising, as its general elements, a rotary casing including a pumpingchamber, means for delivering a fluid to be pumped to the pumpingchamber, a discharge duct coaxial with the rotary casing, and astationary pitot tube in the rotary casing for picking up fluid adjacentthe periphery ofthe casing with a ram effect and for delivering thefluid to the discharge duct. More particularly, the pitot tube extendsradially ofthe rotary casing and is provided adjacent its outer end withan inlet adjacent the periphery of the rotary casing and facing in adirection opposite to the direction of rotation ofthe rotary casing. Thepitot tube is provided adjacent its inner end with an outletcommunicating with the discharge duct.

Centrifugal pumps of the foregoing type are well known and have theadvantage of providing a very simple structure for pumping fluids athigh pressures and in relatively large volumes. A pitot pump typical ofthe prior art is disclosed in U.S. Pat. No. 3,384,024, granted May 2l,i968 to William L. King.

The above King patent discloses a pitot pump in which fluid to be pumpedis supplied to the periphery of the pumping chamber through radialpassages enclosed within an end wall of the rotary casing. Anothercommon way to supply such fluid to the periphery of the pumping chamberof such a pump is merely between thin radial vanes attached to the innersurface of one or both side walls of the pumping chamber as shown), forexample in the U.S. Pat. to Singelmann, No. 3,049,081, issued Aug. i4,i962, and the Great Britain Pat. No. 737,933, published Oct. 5, 1955,hereinafter referred to as vane type". pumps.

v A primary ydifficulty with such vane type pumps is the accumulation ofair in the rotary pumping chamber, as explained in the US. Pat. toMacklis, No. 3,004,495,

issued Oct. 17, 1961, which provides positive means for continuouslypurging the pump chamber of such accumulated air.

Such vane type pitot pumps are relatively inefficient, due to fluidturbulence created in the pumping chamber by their vanes. Pumps of thetype disclosed in said King patent are relatively expensive to build.

THE INVENTlON GENERALLY The primary object of this invention is toprovide a pitot type pump of the general type disclosed in said Kingpatent, but in which the generally radial passages supplying fluid ytobe pumped to the periphery of the pumping chamber are slots left open onthe side of each facing the pumping chamber and in direct communicaltion with the chamber throughout the length of each, therebysubstantially reducing the cost of manufacture of such a pump, ascompared with the pump of the King patent.

Another object of the invention is to providel such substantially radialslots of substantially uniform cross section throughout the length ofeach, each slot being formed in an end wall of the rotary casing of thepump, to avoid the inefficiency of said prior art vane type pumpsresulting from the fluid turbulence created by the use of radial vaneswith diverging wall spaces therebetween.

A further object of such radial slots is to continuously purge the pumpof any gas accumulating in the liquid being pumped.

The foregoing objects, advantages, features and results of the presentinvention, together with various other objects, advantages, features andresults which will be evident to those skilled in the pitot pump art inthe light of this disclosure, may be achieved with the exemplaryembodiment of the invention illustrated in the accompanying drawings anddescribed in detail hereinafter.

DESCREPTION OF DRAWINGS FIG. l is a longitudinal sectional view ofapitot pump which embodies the invention; and

FIG. 2 is a vertical sectional view taken on the line 2-2 of FIG; l.

DETAILED DESCRIPTION OF INVENTION Referring to FIG. l of the drawings,illustrated therein is a pitot pump 20 comprising an outer housing 22containing a rotary casing 24. ln the particular constructionillustrated, the rotary casing 24 is driven by an electric motor 26mounted. on the housing 22, the rotary Casing being supported by themotor shaft 28. However, it will be understood that the rotary casing 24may be mounted on bearings within the housing 22 itself.

The housing 22 is provided with an inlet 30 for the fluid to be pumped,which inlet communicates with a chamber 32 leading to an annular passage34 extending into one end wall 36 of the rotary casing 24. Within suchend wall are generally radial slots 38 which communicate at their innerends with the annular passage 34 and which communicate at their outerends with the periphery of a pumping chamber 39 of the casing 24.

Within the pumping chamber 39 is a stationary pitot or pickup tube 40,which is radially oriented and is provided adjacent its outer end withan inlet 42 facing in a direction opposite to the direction of rotationof the rotary casing 24. The pitot tube 40 is provided adjacent itsinner end with an outlet 44 coaxial with the rotary casing 24 andcommunicating with a discharge duct 46, also coaxial with the rotarycasing 24, leading to an outlet 48 in the housing 22. The annularpassage 34 surrounds the discharge duct 46 throughout a portion of thelength of the latter.

The general mode of operation of the pitot pump 20 is well known soythat it does not need to be described in detail. Briefly, thecentrifugal force produced by rotation of the casing 24 generates a highfluid pressure adjacent the outer periphery of the pumping chamber 39.The fluid at this high pressure enters the inlet 42 of the pitot tube40, the pressure being further increased by the ram effect resultingfrom so orienting the inlet 42 that it faces in a direction opposite tothe direction of rotation of the rotary casing 24. The fluid enteringthe pitot tube 40 flows through the outlet 44 and the discharge duct 46to the main outlet 48 in the housing 22. It will be understood that thepitot tube 40 is stationary, being mounted on and suitably secured tothe discharge duct 46.

- As illustrated in FIGS. l and 2, the generally radial slots 38 aresubstantially uniform in cross-sectional area throughout their length,and, except for such slots, .the inner surface 50 of the end wall 36 issubstantially flat and perpendicular to the axis of the pump, which isanother feature of the invention. It is also to be noted from FIG. 2that the slots are not exactly radial with respect to the longitudinalaxis of the pump, but each is angled slightly with respect to a radiusto intersect the annular passage 34 at a slight angle to improve thefeed of fluid to the slots from the annular passage and therethrough,and this is another feature ofthe invention. It is also to be noted fromFIG. 2 that the inner ends of the slots 38 almost join, so that thecombined crosssectional areas of the slots approximately equal the areaof the periphery of the annular passage 34 opposite the slots, and thisis a further feature of the invention, Such slots 38 may be formed bymerely casting them into the inner surface 50 of the end wall 36 of therotary casing, which contributes to the economy of manufacture oftheinvention, another important feature.

Contrary to our expectations, we have found that by leaving the slots 38open on their sides communicating with the pumping chamber 39, there isno substantial loss of fiuid from the slots into the chamber during thepassage of fluid through the slots from their inner to their outer ends,and that most of the fluid flowing in the slots stays therein during itspassage through the slots, with the result that little if any additionalfluid turbulence is created in the pumping chamber by leaving the slotsopen sided, with the final result that the efficiency of our pump isalmost as high as that ofa pump having the slots enclosed, as shown insaid King patent.

Furthermore, we have found by tests that with the use of such openradial slots 38, the pump is continuously self-purging of most gasaccumulating in the flow of liquid being pumped, which otherwise wouldsubstantially reduce pump efficiency, requiring no separate means forsuch purging.

Although an exemplary embodiment of the invention has been disclosed forpurposes of illustration, it will be understood that various changes,modifications and substitutions may be incorporated in such embodimentwithout departing from the spirit of the invention as defined by thefollowing claims.

We claim:

1. In a pitot pump, the combination of:

a rotary casing having an annular pumping chamber therein, one side wallof said chamber being provided with generally radial slots thereinhaving one side throughout its length in open communication with saidchamber, each of said slots being of substantially uniform cross sectionthroughout its length and extending from a point adjacent to therotational axis of said casing to a point adjacent to the innerperiphery of said chamber;

housing means surrounding said rotary casing and having an inlet portand a discharge port;

a tubular member rigidly mounted on said housing and extending into saidchamber, there being an annular passage around said tubular member andcommunicating between said inlet port and the inner ends of said slots,said tubular member having an axial passage therein communicating at oneend with said discharge port;

a pitot tube rigidly mounted on said tubular member and extendingradially in said chamber, said pitot tube having adjacent its outer enda pitot inlet facing in a direction opposite to the direction ofrotation of said casing, said pitot tube having a central passagetherein communicating between said pitot inlet and the other end of saidaxial passage; and

drive means extending into said housing and rigidly connected to saidcasing for rotating said casing.

2. A device as defined in claim l in which said side wall of the pumpingchamber is substantially flat, except for said slots therein, andsubstantially perpendicular to the rotational axis of said casing.

3. A device as defined in claim l in which each of said slots isoriented at an angle to a radius through the rotational axis of thecasing and the inner end of the slot in a direction opposite to thedirection of rotation of said casing, to provide the inner end of eachslot with a scoop effect on fluid in said annular passage.

4. A device as defined in claim i in which the combined cross-sectionalarea of the inner ends of said slots is substantially equal to the totalannular area of said annular passage intersected by said slots.

i l a t

1. In a pitot pump, the combination of: a rotary casing having anannular pumping chamber therein, one side wall of said chamber beingprovided with generally radial slots therein having one side throughoutits length in open communication with said chamber, each of said slotsbeing of substantially uniform cross section throughout its length andextending from a point adjacent to the rotational axis of said casing toa point adjacent to the inner periphery of said chamber; housing meanssurrounding said rotary casing and having an inlet port and a dischargeport; a tubular member rigidly mounted on said housing and extendinginto said chamber, there being an annular passage around said tubularmember and communicating between said inlet port and the inner ends ofsaid slots, said tubular member having an axial passage thereincommunicating at one end with said discharge port; a pitot tube rigidlymounted on said tubular member and extending radially in said chamber,said pitot tube having adjacent its outer end a pitot inlet facing in adirection opposite to the direction of rotation of said casing, saidpitot tube having a central passage therein communicating between saidpitot inlet and the other end of said axial passage; and drive meansextending into said housing and rigidly connected to said casing forrotating said casing.
 2. A device as defined in claim 1 in which saidside wall of the pumping chamber is substantially flat, except for saidslots therein, and substantially perpendicular to the rotational axis ofsaid casing.
 3. A device as defined in claim 1 in which each of saidslots is oriented at an angle to a radius through the rotational axis ofthe casing and the inner end of the slot in a direction opposite to thedirection of rotation of said casing, to provide the inner end of eachslot with a scoop effect on fluid in said annular passage.
 4. A deviceas defined in claim 1 in which the combined cross-sEctional area of theinner ends of said slots is substantially equal to the total annulararea of said annular passage intersected by said slots.